1. Field of the Invention
This invention relates to optical focusing systems. In particular it relates to holographic optical focusing systems and in even further particularity relates to focusing systems for aerodynamic enclosures such as nose cones of planes, missiles, bombs and so forth.
2. Description of the Prior Art
The use of aerodynamically superior dome shapes in optical missile seekers significantly reduces drag. This results in increased effective range and closing speeds while also reducing rain erosion rates for improved all-weather performance.
For an optical seeker to function properly, the optical effects produced by the dome must be independent of the angle of incidence of the incoming target radiation. This requirement has in the past dictated the use of a hemispherical rather than a more aerodynamic suitable dome shape such as an ogive. The aberrations introduced by aerodynamic frontal enclosure designs cannot be corrected by conventional refractive or reflective optics.
Previous optical focusing systems for aerodynamic structures have required use of conventional lenses and mirrors for optical systems. Lenses have required traditional optical grinding to avoid aberrations and other distortions that destroy the focusing of the image. Use of conventional optics requires the frontal structure to be designed for optimum guidance abilities rather than optimum flight performance of the vehicle. Flight parameters effected by conventional optics are increased resistance to flight weather, decreased closing speed, decreased flight range, less manuveability, decreased guidance stability, manufacturing simplicity, increased miss distance, and multimode operations. All of these factors have been limited because of loss of guidance capabilities.